Process for the preparation of ethylene sulfide



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*PRQCESSFORTHE-PREPARATION-QF i ,sULrnJE 4 Claims. (Cl. 260-827) This invention concerns a new and improved process for the production of ethylene sulfide.

Ethylene ,sulfide is known as an important organic intermediate. It polymerizes readily to yield polyethylene sulfide which in turn can be converted to derived polymers. In addition, ethylene sulfide is a useful material for destroying vermin and other noxious organisms when used to prepare insecticides, fungicides, and the like. The use of this material in this manner is described in U. S. Patent 2,094,914, U. S.- 2,102,564, and U. S. 2,225,573. In addition, it has been used in numerous synthesis as described in the Journal of the American Chemical Society, volume 70, page 217 (1948).

Due to the structure of ethylene sulfide it is highly reactive and, in fact reacts with itself to polymerize easily. Accordingly, when ethylene sulfide is prepared by methods known in the prior art it has been known to polymerize during the course of preparation. For instance, ethylene sulfide may be prepared as follows:

ClCHzCHzSH NaHCOa CE2-7CH: N801 C O: H2O

When ethylene sulfide is prepared according to this method it must be separated by fractionation to free it from water. This is difficult to do because of the ease with which it polymerizes. In addition, the 2-chloroethylmercaptan is not readily available. I

Other methods of preparing ethylene sulfide are known but some of these either produce small yields or involve difliculties in producing ethylene sulfide without poly- I merization.

I have now discovered a method whereby ethylene sulfide can be obtained in near quantitative yield by decomposition of a new composition of matter. The reaction is as follows:

One object of this invention is to provide a method of obtaining pure ethylene sulfide. Another object of this invention is to provide a new composition of matter, monothiolethylene carbonate. Another object of this invention is to provide a method for manufacturing monothiolethylene carbonate.

In carrying out my invention, I react phosgene with 2- mercaptoethanol to obtain a heterocyclic compound, monothiolethylene carbonate. Heating this material causes it to decompose into ethylene sulfide and carbon dioxide.

Monothiolethylene carbonate is a high-boiling, stable liquid compound which can be prepared and kept until the ethylene sulfide is needed; then it is only necessary i n t States -P sm lic 2,828,318 Pa ented M 5.119

to heat this intermediate in a suitable apparatus wherein the ethylene sulfide can he collected. Since ethylene sulfide cannot be kept because of its tendency to polymerize,

- this "provides a quick and convenient source for it. In

addition,- monothiole-thylene carbonate will undergo reactions 'with other compounds. For instance, it will react with amines to yield mercaptoethylurethanes.

'hibits the decomposition.

The following examples are intended to illustrate my invention but not to limit it in any way:

Example 1.-Monothiolethylene Carbonate One mole (78 g.) of Z-mercaptoethahol, two moles (158 g.) of pyridine and two hundred ml. of ethyl acetate were stirred together in a three-necked flask equipped with a mechanical stirrer, a thermometer and a dropping funnel. With the reaction temperature maintained at 10-20, a cold solution of 100 g. of phosgene in 300 ml. of ethyl acetate was added dropwise. phosgene had been added, the ice bath was removed and the reaction mixture was stirred for an additional hour. It was then filtered and the filtrate was washed by stirring with an equal volume of cold water. The ethyl acetate layer was separated and dried over anhydrous magnesium sulfate. After removal of the ethyl acetate by distillation under vacuum while heating on a steam bath the residual product was distilled. The monothiolethylene carbonate distilled at 4750 at 0.08 mm. Yield 58 g.; n =1.5092.

A second fraction was collected at 50-64 at 0.08 mm. Yield 5 g.; n =1.5089.

The residue which remained in the distilling flask was a viscous, straw-colored polymer formed by linear rather than cyclic condensation. It weighed 27 g.; n =1.5392.

Example 2.-M0n0thi0lethylene carbonate One hundred and fifty-eight grams of pyridine and 300 ml. of ethyl acetate were stirred in the above type apparatus. A solution of 100 g. of phosgene in 300 ml. of ethyl acetate was cooled in a Dry Ice-acetone mixture and 78 g. of Z-mercaptoethanol was added to it. This solution was kept cold and gradually added to the stirred pyridine solution. The reaction temperature was maintained at 1525. After all of the phosgene solution had been added, the reaction mixture was stirred for thirty minutes at 35 and then washed up as in the previous example. The yield was 53 g. of monothiolethylene carbonate, n =1.5107 and 30 g. of polymeric residue.

Example 3.Ethylene sulfide Thirty-six grams of monothiolethylene carbonate (Example 1) were placed in a fifty ml. flask with 0.36 g. of

. anhydrous sodium carbonate and some bumping stones.

Example 4.Ethylene sulfide Ten grams of monothiolethylene carbonate (Example 2) were heated as in Example 3 with 0.1 g. of anhydrous After all of the sodium carbonate. Yield, 4.8 g.; n =1.4895 (83.2%). v 2. A process for the preparation of monothiolethylene There was no polymerization. carbonate comprising reacting phosgene and Z-mercapto- Example ip-Ethylene sulfide v i ethanol 3. A process for the production of ethylene sulfide T grams f monothiolethylene elE mpl 5 comprising heating monothiolethylene carbonate until it 2 were heated without sodium carbonate. In one case decomposes.

V PO S p gsto Was used and in an S Dnd case 4. A process for the production of .ethylene sulfide a granite-like mp S ne was added. Intthe former i comprising reacting phosgene and Z-mercaptoethanol to case 4.6 g. (79.5%) was Obtained; nD =1- 895and in form monothiolethylene carbonate, followed by heating the latter experiment 4.8g. (83.2%) having n V =L4895 10 the monothiolethylene carbonate at its decomposition was obtained. There was no polymerization during the temperature. 7 preparation. V 1 i l The temperatures indicatedherein are centigrade r N9 F P$ I claim; e

1. Monothiolethylene carbonate. 7 15 

4. A PROCESS FOR THE PRODUCTION OF ETHYLENE SULFIDE COMPRISING REACTING PHOSGENE AND 2-MERCAPTOETHANOL TO FORM MONOTHIOLETHYLENE CARBONATE, FOLLOWED BY HEATING THE MONOTHIOLETHYLENE CARBONATE AT ITS DECOMPOSITION TEMPERATURE. 